Heretofore, in the precision mechanical industry, the optical instrument industry, the electrical and electronics industry or the plastics industry, for precision cleaning to remove oil, flux, dust, wax or the like attached during manufacturing processes, a hydrochlorofluorocarbon (hereinafter referred to as HCFC) such as dichloropentafluoropropane (hereinafter referred to as R-225) has been widely employed as a fluorinated solvent which is nonflammable and excellent in chemical and heat stability and which is capable of dissolving oils and greases.
However, there is a problem that HCFC has an ozone depleting potential, and its production is expected to be abolished in advanced countries by year of 2020. Whereas, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (CHF2CF2OCH2CF3) is a fluorinated solvent which has no ozone depleting potential and which presents little impact to the global environment, but it has a problem that its solvency for oils and greases is low. On the other hand, trans-1,2-dichloroethylene has a high solvency for oils and greases, but it has a problem that its flash point is as low as 4° C.
Further, an azeotrope of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether and trans-1,2-dichloroethylene is known (see claim 3 of JP-A-10-324652). The above mixture is nonflammable and has an excellent cleaning performance, but it has a problem such that e.g. in defluxing, removal of ionic soil tends to be inadequate, or white residues tend to remain.